Re: gEDA-user: Interesting board defect

[Gabriel Paubert <paubert@xxxxxxx>]

On Mon, Feb 16, 2009 at 05:36:02PM +0100, Stefan Salewski wrote:
> Am Montag, den 16.02.2009, 09:50 +0000 schrieb Dylan Smith:
> > On Sat, 14 Feb 2009, Dave N6NZ wrote:
> > 
> > On Chinese fabs...
> > 
> > > So... it's hard to beat BatchPCB's price for one-offs, but I've decided
> > > to dial back a bit on how hard I push their technology.  I've never
> > > gotten a straight answer from them anyway on design rule questions.
> > 
> > I've used PCB Cart for a few boards (dealt with them directly). They
> > probably are a bit more expensive for one-offs, but the boards I got back
> > for a project using 0.4mm pitch LQFP (a 4 layer board) with minimum DRC
> > trace/clearance of 6/6 came back from them perfect. They seem very
> > flexible and don't have any odd design rules. They do free electrical
> > testing for boards that are 4 layers or more.
> > 
> 
> Interesting.
> 
> I consider using PCB Cart myself -- price is good, and I heard that
> quality and support is fine too.

Here in Spain, I have ordered a few 4 layer boards for prototype
from multipcb.de and am rather satisfied. The cost of their Single-Pool
is really good for 1 or 2 four layer boards since they have zero tooling 
cost. Mine was a bit more expensive (silskscreen on both sides) but 
still very reasonable, about 10WD (2 days shipping).

> 
> I have a 4 layer board too.
> 
> Have you send gerbers from PCB program?

Yes.

> Is there something special to watch for?

Not that I am aware of. I was using 150/150 micron rules, at least
in the area of the power supply using a 0.65mm pitch package with 
1.5 amp in many pins, so I was stressing more the minimal spacing
than the minimal linewidth. 

> 
> I think they have no information for impedance control on their page (we
> need to know layer separation to calculate impedance). Have you manage
> to get defined impedances for your traces?

Did not nee for this, and my RF designs use Rogers' substrates which
are much more reproducible than FR4 at frequencies above 2GHz.

	Gabriel


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